An electrodeless dielectrophoresis (EDEP) microchip is proposed for the concentration of nanoscale particles and proteins in a 150 nm nanoconstriction gap in a microchannel. Notably, the nanoconstriction is fabricated using a simple thermal-oxidation shrinkage process. It is shown that the nanoconstriction enhances the local electric field intensity by a factor of 1 × 103. The strong electric field and field gradient result in concentration enrichment by factors 1 × 104 and 1 × 103 for nanoparticles and proteins, respectively, within 30 s. Thus, the proposed EDEP chip has significant potential for achieving rapid and highly sensitive protein detection and for biomarker discovery applications.

A three-dimensional electrodeless dielectrophoresis (EDEP) device incorporating a micrometer-sized constriction region is proposed for the rapid preconcentration of protein. The electrokinetic phenomena within the proposed device are investigated both numerically and experimentally. It is shown that the micro-constriction structure increases the field-focusing factor by around 15 000 times and yields a 106-fold increase in the concentration of streptavidin protein within 36 s. Overall, the proposed device provides a low-cost and effective solution for performing highly-sensitive protein detection and overcomes the Poisson statistical limit inherent in traditional two-dimensional (2D) EDEP devices through its support of large (ml-scale) sample volumes.